Electric furnace



Oct. 26 y1926.

W. J. SCHULTZ ELECTRIC FURNACE Filed sept. 251 1925 4 snepfts-sheet 1'umm w. J. SCHUL-rz ELECTRIC FURNACE Filed Sept. 25. 1925 oct. 26 1926.

4 Sheets-Sheet 2 INVENTOR Get. Z6 1926.

W. J. SCHULTZ ELECTRIC FURNACE Filed Sept. 25. 1925 4 Shee ts-Sheet 3 w.J. scHULTz ELECTRIC FURNACE Oct. 26 1926.

Filed Sept. 25, 1925 4 Sheets-Sheet 4 INVENTOR MYV iw Patented Goto' 2d,i926..

unirse stares FFCE' WILLIAM J'. SCHULTZ, OF McKEESPOB/l, PENNSYLVANIA,ASSIG'VNOR TO FIRTH STER- LING STEEL COMPANY, F MGKEESPORT,PENNSYLVANIA, A CORPORATION 0F PENNSYLVANIA.

ELECTRIC .'FUBN-ACE.

Application led September 25, 1925. Serial No. 58,504.

The present invention relates broadly to electric furnaces, andparticularly to furnaces of the electrode type.

One ofthe greatest difficulties encountered l in the operationL ofelectric furnaces of the electrode type is the control of the electrodewith respect to thebath of metal. lit is customary to use motor drivendevices, usually cables and cabledrums, to raise an.

lower the electrodes'. lnasmuch as the electrodes require a relativelyslight movement, the adjusting motor is usually geared to a ycable drumthrough a worm drive or other low ratio gear. The high speed of thearmature is thus transmitted as a slow motion.

This speed of the armature, however, presents serious diiicultiesbecause of the over travel which it necessarily causes, that is, a motorgoing at` even moderate speed cannot be instantly stopped and anydrifting of the motor after the current is cut oli" represents overtravel of the electrodes. Dynamic braking is not always effectualbecause the retarding current becomes very weak with `reduced speed, anda heavy armature and hand wheel represent considerable inertial energyat the lower speeds where dynamic breaking is least efficient.

I propose to obviate the evil effects of the inertia forces vof thearmature and gearing by providing an electrode controlling mechanismwhich can be disengaged from the driving motor when the desiredelectrode travel has been effected. l further provide for engaging thehand wheel which is used for manual operation only whenI it is desiredto adjust the electrodes, so there will be no inertia effect from thehand wheel when the motor is operating.

I further provide stability ofthe electrodesand insure theirabsolutecontrol by a construction on the supporting mast which causesthe electrodes to alwa s` maintain themselvesin proper alignment y theirown weight.

Furthermore, I secure absolute control of the electrodes by theprovision of an yimproved insulating joint between the electrode holderand its supporting arm, whereby l rotation of the electrode holder aboutthe supporting arm is prevented. l

' In the accompanying drawings, illustratinvention,-

Figure Lis a side elevation of an electric furnace embodying myinvention;

Figure 2 is a top plan view of the furnace shown in Figure 1;

Figure 3 is a rear elevation of thefurnace; Fi ure 4 is a sectional viewon the line d IV- V of Figure 3;

Figure 5 is a sectional view` showing the connection between the carbonholder supporting arm and the mast;

Figure 6 is a top plan view of an electrode holder; 1

Figure 7 is a sectional view of the electrode holder shown in Figure 6;v

Figure 8 is a cross section on the line VIII- VIII of Figure 7 g Figure9 is a diagrammatic view of the gesr box used to control the electrodehoist; an Y a Figure 10 is a wiring diagram of the control systemapplied to one electrode.

In the illustrated embodiment, Figure l shows an electric furnace havinga body portion 2, a removable top 3 fitted with water-jacketed collars4through which protrude the electrodes 5. The electrodes 5 are carried inthe electrode holder 6 which are carried by, but insulated from,supporting arms 7. rlhe supporting arms 7 are connected with verticalmasts 8 by means of a T-connection 9, as clearly illustrated in Fig-'ure 5. The masts 8 are freeto move in a vertical direction only, beingrestrained lfrom any side movement by means of rollers ing'the presentpreferred embodiment of my p over a pulley 13 to a hoist drum 14.`l Thehoist drum 14 is controlled by a ear box, as will be hereinafter morefully escribed.

The body portion 2 is fitted with brackets 15 and 16. These brackets areeffective for holding the mast guides 17 and for support- 'ing 'thecontrol platform 18. The control platform 18 is used for mounting all ofthe mechanism required for controlling the electrodes, since thismechanism must rotate with the furnace body. Suspended from the platform18 is a driving motor 19 which lCurrent; is supplied to the electrodesby means of-bus bars 29 through iiexible cables 30. The bus bars 29 aresupported on the electrode holder supporting arms 7 by means of brackets31 which are insulated from the supporting arms 7 vby clamping suitableinsulating material between the brackets 31 and arms 7, as is shown inFigure 5. The bus bars 29 terminate' on the electrode holder 6 inbrackets 32, as shown in Figure 7. l

The usual method of supporting the electrode holder from its supportingarm involves :flanged couplings and bolts, each of which must beinsulated. As will be seen from Figures 7 and 8, I provide a muchsimpler construction. I prefer to make the horlzontal supporting arm 7of heavy tubing. The end of the tubing is crimped to form a' series ofrounded ridges and depressions, as shown in Figure 8. The electrodeholder, 6 is formed to cooperate with this 4 construction and bolts 33are provided for drawing the end of the electrode holder tightly aboutthe supporting arm 7. Insulation is provided by placing some heatresisting insulation 34 about the corrugated portion of the supportingarm and conform ing it thereto prior to the application of the clampingend of the electrode holder. The end of the tubing 7 may be insulatedfrom the electrode holder by means of a piece of suitableinsulationplaced between the electrode holder and the end of the arm, asshown in Figure 7. This type of construction provides a connection whichis secure against rotation and free from electrical` defects. At thesame time, the holder 6 is readily removable if so desired. The arm 7,it will be noted, is prevented from rotation by means of a pin 35 whichprojects through the T-shaped connection 9 as shown in Figure 5.

- The electrode holder is'provided with the usual water connections 36and electrode Water for cooling the electrode holder 6 yis providedthrough suitable pipes 39 which lead to hose connections 40. A supply ofwater for each holder is insured by running a separate pipe thereto.Waste water from V the electrode holder 6 is led through hoseconnections 41 through the guide collars 4 from whence the waste wateris led to a common'waste pipe'42.

placed on the mast so that the weight of the p electrode and itssupporting arn and associated parts at all times hold the recess 43 inclose contact with the rollers 10, thereby forming a self-aligningconstruction.

Figure 9 clearly illustrates the mechanism controlling-the cable drum14. shaft 2O 'rotating continuously at constant speed, has splinedthereon a collar 44 rotating with the shaft and free to move axiallythereon. Both sides of the collar 44 are provided with lugs 45 which maycooperate with corresponding lugs 45a on the internal faces of bevelgears 46 and 47 which are mounted in opposed relationship on the shaft2() -and are free to rotate thereon. The bevel gears 46 and 47 arecontinuously in mesh with a corresponding bevel gear 48 mounted on ashaft 49 perpendicular to the shaft 20. The shaft 49, by means of a Worm50 and a worm wheel 51, drives a shaft 52 which carriesthe cable drum14. As will be evident from the drawings, axial movement of the collar44 is controlled by a forked arm 53, whichin turn may be moved by a handlever 54 or a cross arm 55. The cross arm 55 may be moved selectivelyclockwise or anti-clockwise by armatures 56 which are controlled bysolenoids 57. It is evident that the bevel gear 48 and, consequently,the cable drum 14, may be rotated in reverse direction by engagingeither of the bevel gears 46 or 47 fwith the collar 44. The drum 14cannot be operated by tension on the cable 11 because of the frictionbetween the Worm 50 and the Worm wheel 5l. For convenience in mounting,I prefer to place the solenoids 57 below the control platform 18, asshown in Figure 1.

l provide for manual adjustment of the electrodes by means of a handwheel 58 mounted on a shaft 59 and controlling a spur gear 60. The spurgear 60 engages a corresponding gear 61 mounted cn the shaft 49. Thedrawing shows the manual control mechanism in position for operating.When the elevation of the electrodes 5 is being "controlledby thesolenoids 57, all of the The electrodes. 4Control of the electrode fedby bus 64 is eected by'means of current taken from that bus through atransformer 65. The current'passing through the secondary of transformer65 is led through a solenoid 66 andl also through a variable resistance67. The adjustable resistance 67 parallels the solenoid 66, so that thestrength of field of the solenoid may be controlled by adjusting theresistance 67. The solenoid 66 con'- trols an armature 68 which actsthrough a lever 69 to control a contact linger 70. Rapid oscillation ofthe lever 69 is prevented by means of fa dash pot 71. It will beunderstoodthat the control mechanism thus far described is of a'sensitive nature and operates on a reduced current. To prevent arcingand consequent destruction of vthe contact finger 70, a step-down'transformer 72 is provided. This transformer takes the current from asuitable source 73 and supplies what current is necessary to operatethe'relays 74 and 75. These relays are controlled selectively throughcontacts 76 and 77 by means of the contact finger 70.

The heavier current required to operate the solenoids 57. is taken fromthe source 73 and controlled selectively by the relays 74 a controlwhereby the direct current was,

shut olf in case the alternating' current failed This was true becausethe 'effect of 'a reduced current through the busses 62, 68 and 64 is tocause the control mechanism to lower the electrode, and in the eventthat the alternating current failed the direct current control systemcaused 'the electrode to plunge into the bath. With my improved controlsystem a failure of the'alternating current causes the whole mechanismto retheir` control.

^ It will be obvious th`at the gear box might be replaced with conefriction wheels, and

the jaw clutch formed bythe lugs l4:5 and 45a replaced by friction diskclutches without departing from thel spirit of the invention. i

The advantages of the present invention arise from the provision of aconstruction wherein the electrodes in an electric furnace may bemaintained 'in proper alignment, electrically insulated from thestructure and secured against sidewise movement. i

Further advantages arise from the provision of a means whereby theadjustment of the carbon is made accurate and free from the inertia eectof the rotating armature of the driving motor, whereby drifting and overtravel is avoided. j

Still greater accuracy and ease of adjustment is provided in a handoperating mechanism wherein the hand wheel is engaged with the hoistmechanism only when it is desired to operate the electrodes manually. Inthis way I avoid the inertia effect of the spinning hand wheel when thehoist is motor operated.V o

While I have described the present prefer-red embodiment of myinvention, it will be understood that changes may be made in theconstruction disclosed therein and method of working the same withoutdepartinof either from the spirit of the invention ofa the scope of thefollowing claims.

I claim as my invention:

1. The combination with an electric furnace having an adjustableelectrode, of means for advancing or reti-acting the electrode includinga motor, an electrodemoving element driven thereby, and a reversingclutch interposed between the motor and the electrode-moving element. l

2. The combination with an electric furnace having anr adjustableelectrode, of means for advancing or retracting the electrode includinga continuously driven motor, an electrode-moving element driven thereby,a reversing clutch interposed between the motor and the electrode-movingelement, and manually operable electrode adjusting means movable intoand out of driving connection with said electrode-moving element.

3. The combination with an electric furnace having 4an adjustabfeelectrode, of means for advancing or retracting the electrode includingal continuously operating motor, an electrode-moving element driventhereby, a reversing clutch` interposed between the motor and theelectrode-moving element, and electro-magnetic means for operating theclutch.

, 4. The combination with an electric furnace having an adjustableelectrode, of means for advancing or retracting the electrode includinga continuously operating motor', an electrode-moving element driventhereby, a reversing clutch interposed between the motor and theelectrode-moving element, electro-magnetic meansr for opel-at` ing theclutch, and means controlled by a character of lt-he electrode circuitfor con-l trolling said electro-magnetic means.

5. 4The combination with an electric furnace having an adjustableelectrode, of means for advancing or retracting the ele-ctrode including.a continuously operating vmotor, an electrode-moving element driventhereby, a reversing lclutch interposed between the motor and theelectrode-moving element, electro-magnetic means for operating theclutch, means controlled by a character of theV electrode circuit forcontrolling said electro-magnetic means, and electromagnetic means`responsiveto current variations in the electrode circuit forcontrolling the operation of said clutch.

6. The combination with an electric furi nace having an adjustableelectrode, of a' drum, a flexible connection between the drum and theelectrode, a motor -for driving the drum, a reversing clutch between thev motor and the drum, and a control for the clutch. l

7. The cbmbination with an electric furnace having .an elect-rodemovement by gravity in one'direction, of a drum, a cable connecting thedrum and the electrode for raising and lowering the electrode, a wormgear through which the drum is operated, a continuously operable motortor driving the worm, and a reversing clutch interposed between themotor and the worm gear.

8. The combination with an electric furnace having an electrode movementby gravity in one direction, of a drum, a cable4 connecting the drum andthe electrode for raising and loweringtheelectrode, a worm gear throughwhich the drum is operated, a continuously operable motor for drivingthe worm, a" reversing clutch interposed between the motorand the wormgear, and an electro-magnetic control for the cutch.

9. The combination with an electric furnace having an electrode movementby gravity in one direction, of a drum, a cable connecting the drum andthe electrode for raising and lowering the electrode, a worm gearthrough which the drum is operated,

a continuously operable motor for driving the worm, a reversing clutchinterposed bel tween the motor and the worm gear, and

as hand operated mechanism between the worm and clutch for effecting amovement of the Worm, said hand operated mechanism being movable intoand out of driving connectionwith the worm, whereby the worm may beVoperated through the clutch without operation of the hand operatedmechanism. Y

10. The combinationwith an electric fur- 'nace having a plurality ofelectrodes, of'

., means for adjusting the electrodes including a continuousy drivenshaft, a separate electrode moving element for each electrode, areversing clutch between the shaft and each electrode moving element andan indepedent control for each reversing clutch.

11. The combination with an electric furnace having a plurality ofelectrodes, of means for adjusting. the electrodes including acontinuously -driven shaft, a separate electrode moving element for eachelectrode, av

reversing clutch between the shaft and each electrode moving element, anindependentf V control for each reversingclntch, and an electro-magneticmeans for-controlling the operation of each reversing clutch.

12. The combination with an electric furnacehaving a plurality ofelectrodes, of a cable and drum for each electrode' for effecting themovement thereof, acommon driving shaft for transmitting power to eachdrum, and a reversing clutch interposed between the driving shaft-andeach drum.

13. The combination with an electric fur` nace having a plurality ofvertically movable electrodes, of a cable and drum for adjustably movingeach electrode, a worm gear through which each cable and drum isoperated, .-'a common shaft for transmitting 'nsA motion to eachl wormgear, and a reversing clutch interposed between the shaft and eachwormgear- 14. The combination with an electric furnace having at least oneelectrode, of means for raising and lowering the electrode comlnacehaving a plurality of electrodes, of

means for raising and lowering the several electrodes comprising acontinuousl rotating driving element, a plurality o driven elementsconnected tov the respective electrodes, and a plurality of means fortransmitting motion in reverse directions from the driving element tothe driven elements.

17. The combination with an' electric furnace of an electrode, andcontrol means for the electrode including` a laterally projecting arm onwhich the electrode is carried, a longitudinally movable grooved mast towhich the arm is rigidly secured, and guide rollers whereby the mast ismaintained iny a. predetermined path, said guide rollers being shaped,to` cooperate with the grooved mast and prevent rotational movementthereof.

18. The combination with an electric furnace of an electrode, andcontrol meaiis for the electrode lincluding a laterally projectving armon which the electrode is carried, a

longitudinally movable 'mast to which the arm is rigidly secured7longitudinal groovesv von said mast, said grooves being formed withincreasing curvature toward the deepest portion thereof, and guiderollers cooperating with the grooves in the mast, said guide rollersshaped withtransversely curvedsurfaces which engage the grooves inthemast, therebyfmaintaming the mast against lateral displacement andpreventing rotational movement ofthe same.

19. An electric furnace comprisinga furnace structurel having aplurality of opposed rollers therein,. a lon tudinally movable mastguided by said ro lere, a laterally projecting arm secured to the mastand having its outer `projecting` end of non-circular cross-section, alayer ofheat resisting insulation conforming' with the projecting end,and an electrode holder at'the end of the aim `secured thereto by aclamping portion of theholder cooperat-ing with the arm portion ofnon-circular section.

20. An electric furnace comprising a fur- I nace structure havingopposed guide rollers therein, a longitudinally movable mast hav- 111gment with the rollers, a laterally projecting tubular arm secured to themast and having its outer projecting end uted, a layer of heat resistinthe fluted en portion of the arm, an electrode holder at the end of thearm secured thereto by a clamping portion of the holderM Illtesimony u'my an A.

cooperating with the ted portion of the arm.

ves therein for co-operative engageinsulation conforming with.

aty

ductively derived from the same source supi plyi'ng the electrode. J

22. An electric furnace comprising a furnace structure having aguide-way therein, opposed rollers in the guide-way, a mast in theguide-way having grooves therein for cooperative engagement with therollers, a rigid tubular arm having a uted outer end portion secured tothe mast and projecting aterally therefrom, an electrode holder at theend of the arm insulated therefrom and secured thereto 4by a clampingportion of the holder cooperating `with the liuted end portion of thearm, an electrode in the older, means for raising and lowering the mast,said means including a drum, a cable connecting the mast and the drum, acontinuously rotating driving motor, andmeans for intermittentlytransmitting motion in reverse directions from the driving motor to thedrum. v

whereof I have hereunto set WILLIAM J. soHULTz.

